Anybody training for a marathon would benefit from a technique called self-myofascial release. The tissue called fascia that surrounds and connects to muscle is traumatized by running, particularly after long runs, leading to inflammation and painful trigger points. If ignored, trigger points could eventually result in impaired muscle function, tightness, decreased circulation, weakness, and delayed muscle recovery. Ultimately, any one or more of these problems will have a negative impact on running performance.
All that is required to perform self-myofascial release is an inexpensive foam roller and maybe a mat.
Roll your leg muscles over a foam roller, focusing on the most painful spots.Once you find one, stop rolling and hold the pressure for 30 seconds or so, until it appears that the pain is starting to subside. Runners will want to focus on the iliotibial band, all the way from the hip to the knee on the outside of the leg. Quads, calves, hamstrings, piriformis, upper back, and the adductor on the inside of the leg may also need work.
You won't eliminate 100% of the pain right away and you may not be able to hit every spot without visiting a good sports massage therapist, but consistent self treatment with the foam roller should result in healthier muscles and better performance.
If you are traveling, a tennis ball can be used to isolate on some very specific sore spots and a device called The Stick can be used to roll your muscles after a workout.